Formation of ophiolite-bearing sédimentary melanges in the Alpine-type mountains belts:Insights from analogue models and the Apenninic Casanova mélange case study

Orogenic wedges locally present chaotic tectonostratigraphic units that contain exotic blocks of various size, origin, age and lithology, embedded in a sedimentary matrix. The occurrence of ophiolitic blocks, sometimes huge, in such “mélanges" raises questions on i) the mechanisms responsible for the incorporation of oceanic basement rocks into an accretionary wedge and ii) the mechanisms allowing exhumation and redeposition of these exotic elements in mélanges" during wedge growth. To address these questions, we present the results of a series of analog experiments performed to characterize the processes and parameters responsible for accretion, exhumation and tectonosedimentary reworking of oceanic basement lithospheric fragments in an accretionary wedge.